Introducer for endovascular grafts and stents

Abstract

An introducer assembly for introducing a stent-graft ( 70 ) or other device into a vessel of a patient includes a pre-shaped curved cannula ( 60 ) made preferably of a shape memory material. The curved cannula can pull the proximal end ( 74 ) of the stent-graft ( 70 ) against the inner side wall of the vessel thereby to ensure a good leak free connection at this point. The assembly is particularly useful in deploying stent-grafts into the aortic arch.

1. An introducer assembly for introducing a stent-graft or other device into a patient at the patient's aortic arch, including a catheter provided with a flexible device holding portion onto which a device to be introduced into a patient can be placed, the device holding portion being a cannula and being formed in a curve so as to impart a curvature to a device placed thereon and being able to be trained between substantially straight and curved configurations; wherein, in the curved configuration, the device holding portion has a radius of curvature of no more than 3.5 centimeters so as to cause said flexible device holding portion to be trained to the inner curvature of the wall of a curved vessel of a patient. 
     
     
       2. An assembly according to  claim 1 , wherein the device holding portion is operable to be trained between said substantially straight and curved configurations by the introducer assembly. 
     
     
       3. An assembly according to  claim 2 , including an outer sheath within which the catheter can be provided, the catheter being slidable within the outer sheath between a retracted position and an extended deployment position. 
     
     
       4. An assembly according to  claim 2 , including a guide wire including a relatively stiff portion, the device holding portion being provided with a bore therethrough for receiving the guide wire, wherein the guide wire is operable to straighten the device holding portion relative to the guide wire. 
     
     
       5. An assembly according to  claim 4 , wherein the guide wire is relatively stiff for substantially the entirety of its length. 
     
     
       6. An assembly according to  claim 4 , wherein the guide wire is provided with a flexible distal tip portion, wherein the device holding portion is able to bend when disposed over the flexible distal tip portion of the guide wire. 
     
     
       7. An assembly according to  claim 2 , wherein the assembly includes an outer sheath and a guide wire, wherein at least one of the outer sheath and the guide wire acts to straighten the holding portion of the catheter when the latter is held on or in the catheter or guide wire. 
     
     
       8. An assembly according to  7 , wherein the outer sheath and the guide wire are flexible, the device holding portion of the catheter having a lower deflection force than that of at least one of the outer sheath and the guide wire. 
     
     
       9. An assembly according to  claim 8 , wherein the deflection force for deflecting the device holding portion of the catheter is sufficiently lower than the force required to deflect said at least one of the outer sheath and the guide wire to minimise variation to the flexibility of the introducer in operation. 
     
     
       10. An assembly according to  claim 1 , wherein the device holding portion is formed from a shape memory material. 
     
     
       11. An assembly according to  claim 10 , wherein the device holding portion is made of a Nickel Titanium alloy. 
     
     
       12. An assembly according to  claim 10 , wherein the device holding portion is made of a shape memory polymer. 
     
     
       13. An assembly according to  claim 10 , wherein the material of the device holding portion has a transition temperature around body temperature. 
     
     
       14. An assembly according to  claim 10 , wherein the material of the device holding portion has a transition temperature below body temperature. 
     
     
       15. An assembly according to  claim 1 , wherein the device holding portion has a curvature such as to give is substantially a U-shape when unbiased. 
     
     
       16. An assembly according to  claim 1 , wherein the device holding portion has a curvature of greater than 180°. 
     
     
       17. A catheter for an introducer assembly for introducing a stent-graft or other device into a patient at the patient's aortic arch, the catheter including a flexible device holding portion onto which a device to be introduced into a patient can be placed, the device holding portion being a cannula and being formed in a curve so as to impart a curvature to a device placed thereon and being able to be trained between substantially straight and curved configurations; wherein, in the curved configuration, the device holding portion has a radius of curvature of no more than 3.5 centimeters so as to cause said flexible device holding portion to be trained to the inner curvature of the wall of a curved vessel of a patient. 
     
     
       18. A method of deploying a device in a patient, including the steps of: providing an introducer assembly for introducing a stent-graft or other device into a patient, the assembly including a catheter provided with a device holding portion onto which a device to be introduced into a patient is placed, the device holding portion being a cannula and being formed in a curve, the assembly including an outer sheath operable to house the catheter and device and/or a guide wire locatable in a lumen of the device holding portion; the method including the steps of inserting a proximal end of the introducer endoluminally into a patient to the point of a vascular arch, withdrawing the catheter from the outer sheath and/or withdrawing the guide wire from the device holding portion, providing for the device holding portion to curve around the vascular curve, urging an inner edge of the cannula toward an inner curvature of a vascular wall, and releasing the device from the introducer.